Interesting timing of this thread. I just returned from buying a small waterproof "pocket" that hangs from your neck. It is big enough to hold a credit card, license, and some cash. It was 11 dollars and change and I bought it at eastern mountain sports. You can find them on line or at any place that sells kayaks or water related activity gear.
I am sailing on Oct. 27th on Oasis and its my first cruise also. Believe it or not, this has been one of my only concerns of the trip,
what to do with my stuff to keep it safe and dry. So thank you for this thread!